The invention relates to an apparatus for irradiating a substrate, comprising a housing and, within the housing, a receptacle for the substrate to be irradiated with a circular irradiation surface comprising a first semi-circular surface portion and a second semi-circular surface portion, a first emitter for generating optical radiation, having a first emitter tube that is arranged in a plane of curvature extending parallel to the irradiation surface and has an emitter tube end through which power supply means are guided, whereby the receptacle and the first emitter can be moved with respect to each other.
The invention further relates to a use of the apparatus according to embodiments of the invention for irradiating a substrate.
The invention also relates to an emitter for generating optical radiation, comprising an emitter tube that is curved in a plane of curvature and has an emitter tube end through which power supply means are guided, whereby the emitter tube comprises multiple arcuate curved sections each having a radius of curvature.
The apparatuses and/or emitters are used, for example, for drying paints and lacquers, for curing coatings, for heating food products or for processing semiconductor wafers.
Known apparatuses for irradiation and/or thermal treatment of a substrate consist of a process chamber, in which a receptacle for the substrate to be irradiated and at least one optical emitter, for example an infrared emitter, are arranged. Usually, uniform irradiation of the substrate surface or a homogeneous temperature distribution inside the substrate is important for the process result. Uniform irradiation of the substrate surface is therefore desirable as a matter of principle if a homogeneous temperature distribution can be achieved already by this means. However, depending on the process conditions or geometry, e.g. due to evaporation of solvents, shading of radial zones, process gas flow, the homogeneous temperature distribution inside the substrate can be achieved by a radially inhomogeneous irradiation of the substrate.
An irradiation apparatus of the aforementioned type is known, for example, from German published patent application DE 100 51 125 A1. The rapid heating unit for semiconductor wafers disclosed therein comprises a rotatably mounted receptacle for a substrate having a circular irradiation surface and multiple infra-red emitters with a linear, cylindrically-elongated emitter tube made of quartz glass. In order to ensure a uniform radiation distribution, in particular in the case of a rotating substrate, the rapid heating unit has multiple optical emitters arranged parallel to one another; taken together forming a two-dimensional emitter. To further ensure a uniform irradiation on all sides of the substrate, the infrared emitters are arranged in two irradiation planes, namely above and below the irradiation surface.
Due to the two-dimensional array of the infrared emitters, a plurality of infrared emitters is provided in the irradiation apparatus with respect to the surface to be irradiated. The irradiation apparatus also has very high radiated power per unit area. To achieve a homogeneous distribution of the heating power, the heating power of the infrared emitters must therefore be coordinated. This applies especially to the edges of the irradiation surface. An irradiation apparatus with a two-dimensional array of linearly-elongated infrared emitters therefore is complex in terms of design and control technology.
Moreover, in addition to emitters having a linear, cylindrically-elongated emitter tube, the prior art also includes emitters with a circularly curved emitter tube. Accordingly, the teaching of German utility model DE 88 02 042 U1 is an infrared radiation source having an emitter tube that is multiply curved in a plane and has a circular basic shape. The omni-directional emitter is suitable, for example, for heating burners, or for heating of pipe surfaces.
An apparatus for irradiation of wafers is known from Japanese patent application publication JP 63-222430 A, in which multiple emitters having a semi-circular emitter tube are arranged in pairs parallel to an irradiation plane, such that they extend in concentric circles about a center of the irradiation surface.
The teaching of German utility model DE 18 15 946 U is a fluorescent lamp having an emitter tube comprising an illumination length section that is ovally-curved in a plane of curvature.